The super brief science is that your nervous system is divided into two opposing parts - the sympathetic and parasympathetic nervous systems. These systems inhibit the other when the one is activated. Programming in particular activates and works better with the sympathetic "flight-or-flight" nervous system, while eating food (particularly heavy meals) will activate the parasympathetic "rest-and-digest" nervous system.

Plus, removing unnecessary breaks and decisions in your day can help too.